It is known in the art that certain diphenylheterocyclic compounds possess plant growth regulant activity. Belgian Pat. No. 837,454, July 9, 1976, discloses that certain isoxazol-3,5-yl, thiazol-2,4-yl, 1,2,4-triazol-3,5-yl, 1,3,4-thiadiazol or 1,2,4- or 1,3,4-oxadiazolyl compounds are useful in regulating the growth of plants. U.S. Pat. No. 3,471,509 teaches that certain oxadiazole, oxazole and thiadiazol benzoic acids or benzoates are plant growth regulants. These patents do not however teach the substitution of the phenyl radical attached to the parent heterocyclic nucleus with a trifluoromethyl moiety. Further, there seems to be no recognition in the art that substitution of a trifluoromethyl moiety at the meta position of the phenyl ring unexpectedly enhances the biological activity of the parent heteroaryl benzoate nucleus.